Multiple master cams for cam grinding machines



' Feb. 14, 1967 J. R. FRIES ETAL 3,303,614

MULTIPLE MASTER CAMS FOR CAM GRINDING MACHINES Filed Aug. 20, 1964 4 Sheets-Sheet l INVENTORQ JOHN R. FRIES RALPH E. PRICE BY JOHN/1. OLLER 77w TTOR Y Feb. 14, 1967 "J. R. FRIES ETAL 3,303,614

MULTIPLE MASTER CAMS FOR CAM GRINDING MACHINES 4 Sheets-Sheet 2 Filed Aug. 20, 1964 INVENTOR JOHN R.FRIES RALPH EFF/CE BY JOHN A. BOLLER TTORNEY Feb. 14, 1967 J. R. FRIES ETAL MULTIPLE MASTER CAMS FOR CAM GRINDING MACHINES Filed Aug. 20, 1964 4 Sheets-Sheet 3 W m W IGCPS Feb. 14, 1967 J. R. FRIES ETAL 3,303,614

MULTIPLE MASTER CAMS FOR CAM GRINDING MACHINES Filed Aug. 20, 1964 4 Sheets-Sheet 4 ATTORNEY United States Patent 3,303,614 MULTIPLE MASTER CAMS FOR CAM GRINDING MACHINES John R. Fries, Ralph E. Price, and John A. Boller, Waynesboro, Pa., assignors to Laudis Tool Company, Waynesboro, Pa.

Filed Aug. 20, 1964, Ser. No. 390,916 9 Claims. (Cl. 51101) The invention relates to machines for grinding cams, particularly the cams of automotive camshafts.

The process of manufacturing automotive camshafts involves first, models of intake and exhaust cam contours, using these models as masters. A master camshaft is ground having a separate master for each cam on the product shaft.

In the grinding of the master camshaft, the model is rotated in engagement with a follower either in the form of a shoe or roller having an arcuate surface of a radius corresponding to the radius of the grinding wheel to be used to grind the product cam. In order to grind the product cam with maximum accuracy, the grinding wheel should by of constant diameter. Since this is impossible, the grinding wheel must be replaced after a certain amount of wear. For example, a full size wheel may be worn to a certain diameter. If the wheel is worn to a smaller diameter, the contour of the product cam would not be ground within specified limits.

According to present practice, the follower used with the model cam has an arcuate surface of a radius of a half-worn wheel. When a wheel is worn to a minimum diameter, it is replaced by a larger wheel.

It is, therefore, an object of the present invention to provide means whereby the grinding wheel for grinding automotive cams may be worn to a smaller diameter before replacement is required.

Another object is to provide multiple sets of master cams, one set for each range of wheel diameters.

The multiple sets of master cams may be formed on separate axially spaced shafts or they may be formed on the same shaft with individual cams of each set arranged alternately on the shaft. This latter method is preferred because in order to change from one set to another, 1t is necessary only to shift the follower roller between adjacent master cams, each of which belongs to a different set. Thereafter, the roller will index relative to the set of master cams to which it has been slu'fted.

Another object is to provide means for shifting the follower roller from one set of master cams to another.

Another object is to provide means for automatically shifting said roller when the grinding wheel has been worn to a predetermined diameter.

FIG. 1 is a plan view of a camshaft grinding machme.

FIG. 2 is a partial plan view showing the master cam roller in engagement with one of two adjacent master cams of different sets, either of which may be used to grind a given product cam depending on the diameter of the grinding wheel.

FIG. 3 is a partial end elevation showing the device for shifting the master cam roller from one set of master cams to another set.

FIG. 4 is a hydraulic and electric circuit.

FIG. 5 is a diagram of apparatus for grinding a master cam for a full size grinding wheel.

FIG. 6 is a diagram of apparatus for grinding a master cam for a half-worn grinding wheel.

The invention consists of a master camshaft having multiple sets of master cams, each set having been produced with a different follower for the model cam. For the purpose of illustration, two sets of master cams are described.

The individual cams of the two sets of master cams are arranged alternately on a common shaft. One set has been ground with a follower corresponding to a full size grinding wheel, the other has been ground with a follower corresponding to a smaller grinding wheel. The diameter of the follower corresponding to the large wheel would be half-way between the maximum and minimum diameter of such a wheel. The diameter of the follower corresponding to the worn wheel would be half-way between the maximum and minimum diameter of such a wheel.

A hydraulic or pneumatic piston connected to a follower through a shifter member serves to shift the roller between adjacent master cams. In one position, it will automatically and successively engage all the master cams of one set. In other positions, it will automatically and successively engage all the cams of the other sets. The signal for shifting the follower roller from one position to another may be provided by limit switches operable from the dressing tool or the wheelbase when either of these is in the position corresponding to a mean diameter grinding wheel. Such limit switches function through solenoid operated reversing valves. The change in position of the wheelbase or dressing tool to accommodate a new and larger grinding wheel is effective through said limit switches to reset the follower roller to the set of master cams corresponding to the larger grinding wheel.

The circuit for operating the roller shifting mechanism includes a contact whereby the roller may be shifted only when the carriage is in one end position or any other time when the shifting does not interfere with the grinding operation. For example, the roller should not be shifted at any time during the grinding of a camshaft. On the other hand, if it is considered necessary to shift the roller before all the cams on the shaft have been ground, control means may be provided for retracting the master cam before the roller can be shifted.

Numeral 10 indicates the bed of a grinding machine. Work carriage 11 has a headstock 12 at one end and a footstock 13 at the other end. He'adstock 12 and footstock 13 have centers 14 and 15 respectively for rotatably supporting camshaft W.

Master camshaft 20 is rotatably mounted in bearings 22 and 23 in headstock 12 in axial alignment with center 14.

The means for rotating master camshaft 20 and camshaft W consists of a motor 21 operable through' a suitable belt drive.

Master camshaft 20 has two sets of contours A and B, arranged alternately on said master camshaft. Contours A are for use with a full size grinding wheel. Contours B are used when grinding wheel 30 has worn to a predetermined smaller diameter.

In FIG. 5, master camshaft 20 is mounted for rotation in axial alignment with model cam 61 which is the same size as the product cam on camshaft W. Master cam contours A and B are ground by means of grinding wheel 60 of substantially the same diameter as follower 25 which is to engage cam contours A and B. For grinding contours A and B, follower roller 62 engaging model cam 61 may have a radius half-way between that of the full size grinding wheel and the minimum diameter wheel which can be used with contours A and B.

In FIG. 6, grinding wheel 60 is shown in engagement with one of the master cam contours B. Follower roller 63 engaging model cam 61, in this case, has a radius equal to the mean radius of a half-worn grinding wheel.

Master cam follower 25 is rotatably and slidably mounted on shaft 26 in a manner disclosed in US. Patent 1,993,854, granted March 12, 1935, and US. Patent 2,323,189, granted January 29, 1943. The means for shifting follower 25 from one master cam to another is also disclosed in the above mentioned patents.

The means for shifting master camshaft toward and from operative engagement with follower consists of a piston and cylinder (not shown) in housing 27, but well known in this type of machine;

Grinding wheel is rotatably mounted on a Wheel support (not shown) for movement toward and from camshaft W.

The means for shifting follower 25 from one set of master cam contours to another is a piston slidably mounted in cylinder 41 and having a slot 42 for receiving follower 25. Cylinder 41 is mounted on and forms a part of bracket 45 which connects follower 25 with the roller indexing device shown in said mentioned US. patents.

Operation Follower 25 is normally in engagement with the set of cam contours A.

When grinding wheel 30 has been reduced by wear and dressing to a smaller diameter, cam 55 on dressing device 56 closes limit switch contact 12LS1 in a circuit to the follower shift right relay 16CR.

This circuit also includes normally opened contacts 15CR1 and 16CR1 in parallel and normally closed contact 17CR1.

Follower 25 cannot be shifted while in engagement with master camshaft 20.

Limit switch 6LS is closed when master cam contours A and follower 25 are separated, to complete a circuit to energize relay 15CR.

Contact 15CR1 completes a circuit through limit switch contact 12LS1 and normally closed contact 17CR1 to energize relay 16CR.

Contact 16CR1 in parallel with contact :15CR1 is a holding contact.

Contacts 16CR3 and 16CR4 complete a circuit to energize valve solenoid 7, shifting valve to the right. In

this position, valve 50 cuts off the supply of fluid under pressure to the left end of valve'70 and connects it with exhaust.

Fluid under pressure is then directed through valve 51 to the right hand end of valve 70, shifting said valve to the left and directing fluid under pressure to the left hand end of piston 40 to shift follower 25 to the rig-ht to operative relation with the master cam contours B.

When grinding wheel 30 is worn to its minimum limit, it is replaced by a new full size wheel.

Dressing device 56 and cam are reset in accordance with the diameter of the full size wheel. Resetting cam 55 closes contact 12LS2 and opens contact 12LS1.

We claim:

1. In a cam grinding machine,

(a) means to minimize the effect of wheel wear on the contour of a product cam comprising (b) multiple sets of master cam contours,

(c) one of which has been ground from a model with a follower having a radius corresponding to an unworn wheel,

(d) another of which has been ground with a follower having a radius correspondingto a partially-worn wheel, a

(.e) a master cam follower for said sets of master cam contours,

(f) and means to shift said follower from one set of master cam contours to another when the grinding wheel wears below a predetermined diameter.

2. In a cam grinding machine,

(a) multiple sets of master cam contours with individual master cams of each set arranged alternately,

(b) one of which has been ground from a model with a follower having a radius corresponding to an unworn wheel,

(c) another of which has been ground with a follower having a radius corresponding to a partially-worn wheel,

(d) a master cam follower for said sets of master cam contours,

(e) and means to change the position of said follower from a master cam contour of one set to the adjacent master cam contour of another set, thus positioning said follower for all other cams in said other set.

3. In a cam grinding machine,

(a) means to minimize the effect of wheel wear on a cam contour comprising (b) multiple sets of master cams,

(c) each of which has been ground using a follower having a diameter corresponding to a particular range of diameter of a grinding wheel,

(d) a master cam follower for said sets of master cams,

(e) and means to shift said master cam follower from one set of master cams to another when a grinding wheel wears below a predetermined diameter.

4. In a cam grinding machine,

(a) means to minimize the effect of wheel wear on cam contours comprising (b) multiple sets of master cams with the individual master cams of each set arranged alternately,

(c) each set of which has been ground using a follower having a diameter corresponding to the range of diameters of a grinding wheel,

(d) a master cam follower for said sets of master cams,

(e) and means to change the position of said master cam follower from the master cams of one set to the adjacent master cams of another set, thus positioning said follower for all other master cams in said other set.

5. In a camshaft grinding machine,

(a) a base,

(b) a grinding wheel support on said base,

(c) a grinding wheel rotatably mounted on said wheel support,

(d) a work support comprising (e) a carriage slidably mounted on said base,

(f) a headstock and a foodstock onsaid carriage for rotatably supporting a camshaft,

(g) a master camshaft on said headstock having multiple master cam contours for each product cam on a camshaft,

(h) a master cam follower,

(i) and means to shift said follower from one master cam contour to another when said grinding wheel has been worn to a predetermined diameter.

6. In a camshaft grinding machine,

(a) a base, 7 I

(b) a grinding wheel support on said base,

(c) a grinding wheel rotatably mounted on said wheel support,

(d) a work support comprising (e) a carriage slidably mountedon said base,

(f) a headstock and a foodstock on said carriage for rotatably supporting a camshaft,

(g) a master camshaft on 'said headstock having multiple master cam contours for each product cam on a camshaft,

(h) a master cam follower,

(i) means to shift said follower from one master cam contour to another when said grinding wheel has been worn to a predetermined diameter including (j) a dressing device having a dressing tool movable toward said grinding wheel,

(k) means to advance said dressing tool from time to time to engage and dress said grinding wheel,

(I) and control means actuated when said dressing tool has advanced to a predetermined point to shift said master cam follower.

7. In a cam grinding machine,

(-a) means to minimize the effect of wheel wear on the contour of a product cam comprising (b) multiple sets of master cam contours,

(c) a master cam follower for said sets of master cam contours,

(d) and means to shift said follower from one set of master cam contours to another when the grinding wheel wears below a predetermined diameter.

8. In a cam grinding machine,

(a) means to minimize the effect of grinding wheel wear on the contour of a product cam comprising (b) multiple sets of master cam contours,

(c) each of which has been ground from a model with a follower having a radius corresponding to a particular range of Wheel diameter,

(d) a master cam follower for all of said sets of master cam contours,

to a redetermnied diameter to shift said master cam follower from one set of master cams to another.

9. In a cam grinding machine,

(a) means to minimize the effect of grinding wheel wear on the contour of a product cam comprising (b) multiple sets of master cam contours,

(c) each of which has been ground from the same model but with a follower of difierent diameter,

(d) a master cam follower for all of said sets of master cam contours,

(e) and means operable when a grinding wheel wears to a predetermined diameter to shift said master cam follower from one set of master cams to another.

References Cited by the Examiner UNITED STATES PATENTS (e) and means operable when a grinding wheel wears 2O LESTER M. SWINGLE, Primary Examiner. 

9. IN A CAM GRINDING MACHINE, (A) MEANS TO MINIMIZE THE EFFECT OF GRINDING WHEEL WEAR ON THE CONTOUR OF A PRODUCT CAM COMPRISING (B) MULTIPLE SETS OF MASTER CAM CONTOURS, (C) EACH OF WHICH HAS BEEN GROUND FROM THE SAME MODEL BUT WITH A FOLLOWER OF DIFFERENT DIAMETER, (D) A MASTER CAM FOLLOWER FOR ALL OF SAID SETS OF MASTER CAM CONTOURS, (E) AND MEANS OPERABLE WHEN A GRINDING WHEEL WEARS TO A PREDETERMINED DIAMETER TO SHIFT SAID MASTER CAM FOLLOWER FROM ONE SET OF MASTER CAMS TO ANOTHER. 